05000313/LER-1980-024-03, During Emergency Feedwater Pump Turbine Drive Surveillance,Pump Tripped on Overspeed.Caused by Five Broken Studs Which Hold Governor Steam Valve to Turbine.All Studs Replaced

During Emergency Feedwater Pump Turbine Drive Surveillance,Pump Tripped on Overspeed.Caused by Five Broken Studs Which Hold Governor Steam Valve to Turbine.All Studs Replaced

ML19347C299
Person / Time
Site:	Arkansas Nuclear
Issue date:	10/09/1980
From:	Bramlett L ARKANSAS POWER & LIGHT CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML19347C297	List:
References
LER-80-024-03X, LER-80-24-3X, NUDOCS 8010170245
Download: ML19347C299 (2)

LER-1980-024, During Emergency Feedwater Pump Turbine Drive Surveillance,Pump Tripped on Overspeed.Caused by Five Broken Studs Which Hold Governor Steam Valve to Turbine.All Studs Replaced

Event date:
Report date:
3131980024R03 - NRC Website

text

UPDATE REPORT - PREVIOUS REPORT DATE 9/24/80 D

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8 EVENT DESCRIPTION AND PRO 8 ABLE CONSEQUENCES h's FETT1 I At the start of P-7A (Emergency Feed Water Pump, Turbine Drive) Surveil-I ran i lance, the pump tripped on overspeed.

The pump trip device was immedi-i I ately reset & the Dumo was successfully started.

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r a i s i i was operable. There have been no similar occurrences.

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3J 34 JS 36 Ji 40 41 42 43 44 47 CAUSE DESCAiPTION AND CORRECOVE ACTIONS h 8 I Investigation revealed that 5 out of 8 studs which hold the governor i

FrTT1 i steam valve to the turbine were broken.

This is believed to be the i

rrrn I cause of the oversDeed trio since the trio arm is linked to the 1

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LER 50-313/80-024/03 XR2.

10-9-80 Cause Description & Corrective Action ANO-Unit 1 BY:

L. S. Bramlett The failure analysis yielded the following chemical makeup of the bolts compared to the requirements of AISI C1117 m.aterial.

ELEMENT AISI C1117 SPEC.

BOLT CHEMISTRY Carbon

.14

.20%

.07%

Phosphorous

.04 Max.

.07%

Sulfur

.08

.13

.31 Manganese 1.0 - 1.30 1.0 Silicon

.01 Chromium

.01 Molybdenum

.01 Since the bolt material was detennined to be inferior to the AISI C1117 specifications, they were replaced with an ASTM

. A 193 B7 material. This material is an upgrade to the AISI C1117 material. Also the governor valve bonnet studs, the outer casing studs, and the carbon ring casing studs were replaced with the upgraded ASTM A 193 B7 material.

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